Pintle porting



Patented Mar. 2, 1948 PINTLE PORTING George M. Geiger and Walter Ernst, Mount Gilead, Ohio, assignors to H-P-M Development Corporation,'Wilmington, Del., a corporation of Delaware. y

Application October 27, 1944, Serial No. 560,676

Figure 1 is a transverse section through a radial pump having a porting arrangement according to this invention;

Figure 2 is a longitudinal section through the pintle of the pump of Figure 1 and is'indicated by the line 2-2 on Figure l;

Figure 3 is an enlargement of a'portion oi' Fig` ure I showing more particularly the pintle and the porting arrangement therein;

Figure 4 is a plan view over a portion of the pintle showing one of the ports, therein; and

Figure `5 is a. section through a pintle similar to Figure 3 but: showing a modiiled porting arrangement. Y

Referring to the drawings more in detail, there is shown in Figures 1 and 2 a fluid operable pump comprising a casing l0 having rotatably mounted therein a rotor I2, the latter being supported on antifriction bearings I4 as indicated in Figure 2.

The rotor is radially bored with a plurality of cylinder bores I6 within which are reciprocably mounted a plurality of pistons I8. The pistons I8 comprise an inner portion adapted to be re` ceived within the cylinder I6 and an outer portion which comprises a cross head or shoe portion adapted to be received within the slots 22 of the segmented ring 24.

The ring 24 is retained within a member 26 which is guided on a pair of opposed flats 28 within the casing I0. The ring 24 is rotatable within the member 26 and, to that end, is mounted on suitable antifriction bearings, not shown.

The rotor I2 is centrally axially bored at 30' to receive a pintle or valve member 32. `The member 32 is mounted within the casing in any suitable manner and the aforementioned antifriction bearings I4 are mounted thereon." The valve cylinder bores IS through the apertures 40 lin the lower ends thereof. j

The pintle or valve member 32 is likewise Vprovided with a pair of bores 42 which communicate the port 44 in the casing I0 with the port 46 of the member 32. The ports 46 and 38 are preferably arranged diametrically opposite on the member 32.

Suitable control means such as the rods 48 and 3o may be provided whichextend through apertures in the casing and engage the member 26. By this means, the member 26 may be moved in response to'any predetermined stimuli in order to vary the eccentricity of the ring. 24 relative to the rotor I2 and valve member 32. In a manner well known in the art, the shifting of the ring 24 to vary its eccentricity is ciective to vary the rate of discharge of the pump.

Assuming that the rotor in Figure 1 rotates in a counter-clockwise direction, the cylinders in communication with the lower port 38 are withdrawing fiuid therefrom while the cylinder bores in communication with the upper port 48 are expelling fluid therein. Thus, iiuid is continuously I drawn in through the port 36 and expelled, at

increased pressure, through the port 46.

It has been found that pump units of the type disclosed in Figures 1 and 2 operate with considerable noise whenever the pump is kunder load. or is discharging uid, even if the said load is light. Numerous experiments have been conducted in order to ascertain they exact cause of these noises in order, if possible, to eliminate them. It has been found that, in the usual type radial pump having a space between the suction and discharge ports greater than the diameter of the bores 40, considerable noise is caused by the fact that the cylinder cavity is not completely filledV before the same is sealed of! from the suction port. When the cylinder chamber is sealed ofi' from the suction port before the piston has completed its outward movement, a vacuum is drawn within the cylinder which, upon being relieved as the cylinder moves toward the discharge port, creates an ob- .iectionable noise.

This phenomenon is known as cavitation and it has been established that it is the principal source of noise in a radial pump whenthe same is discharging under low pressures.

It will also be apparent that a certain volumetric loss will take place when the phenomenon of cavitation occurs. Accordingly, an arrangement which would eliminate cavitation would tend not only to reduce kthe generatedl noises but would also increase the volumetric ei'ciency of the pumping unit.

We have found, by experiment and test, that a porting arrangement substantially as shown in Figure 3 is effective largely to eliminate cavitation and the noises therefrom in a radial pump. In this figure a suction port 38 is so arranged that the port 40A of the cylinder which is at the point of being sealed of! from the suction port is beyond the center line B before the said sealing oil is accomplished. This is effected by cutting i back the right hand edge of the suction port so that there is substantial communication between the suction port and the cylinder -until after the piston associated with the said cylinder has com-` may be so arranged that the portion 52 of the valve member between the suction and discharge ports is of substantially the same length as the diameter of the ports 40 at the cylinders I6. We have found, however, that the length of the space 52 may be somewhat less than the diameter of the port without materially affecting the capacity or eiiiciency of the pumping unit.

The utility of the porting arrangement shown in Figure 3 is further increased if the leading, or

, left hand edge of the port 38 is formed so as to be symmetricarwith the right hand edge thereof. With the port so shaped it is possible to` drive the rotor I2 in either direction by shifting the ring 24 so as to lay on the opposite side of the center line.

A somewhat modified porting arrangement is shown in Figure 5 wherein the suction port 38h and the discharge port 46h of the valve member 32h are similarly shaped and symmetrically located with respect to the horizontal and vertical center lines of the valve member. In Figure 5 the lap portion B2b is substantially equal to the diameter of the apertures 40h in the lower ends of the cylinders.

In the arrangement of Figure 5 the cylinders are in communication withthe suction port until they are coaxialV with the horizontal center line of the valve member. Thus, cavitation and the noise caused thereby is substantially eliminated. It will be apparent that, while the arrangement of Figure 3 is such that the port 38 must always be on the'suction side of the pump, the arrangement of Figure 5 permits either the port 38h or the port 48h to act as the suction port. Thus, while the arrangement of Figure 3 permits the ring 24 to be shifted to only one sideof center for a given direction of rotation of the rotor, the shift ring associated with the arrangement of Figure 5 is shiftable across center so that the delivery of the pump may be reversed at will.

Accordingly, we prefer the arrangement shown in Figure 3 for a one-way delivery pump and the arrangement shown in Figure 5 for atwo-way delivery or reversible pump.

As an example of the improvement in the operating characteristics of a pump provided with the improved design of suction ports, a

pump having standard ports according to the prior art was found to operate at a noise level of approximately 96 decibels, while the same pump with a valve member having a suction port formed according to this invention was found to operate at a noise level of only 77 decibels. These readings were recorded with the pumps discharging at their maximum rate and under relatively low pressures.

At the same time, a somewhat increased'rate of discharge was noted, indicating that the improved porting arrangement had eliminated cavitation and provided an arrangement somewhat more efcient volumetrically as well as quieter in operation.

It will be apparent that the particular arrangement set forth in the drawings is not necessarily the only possible means by which the objects of this invention may be accomplished. For example, We have found that certain improved results are obtained in a pump having a standard valve member if the latter is rotated in the direction of rotation of the rotor so that the communication between the suction port and the cylinders is not cut off'prior to the said cylinders passing the horizontal center line of the pump unit. Likewise, so long as the porting arrangement is not varied, and should it be necessary in order to increase the strength of the valve member, the particular shape of the solid web portion of the valve member may be varied without in any way departing from the scope of this invention.

Accordingly,v we desire to comprehend such modifications in structure and arrangement and l substitution of equivalents as maybe considered to come within the scope of the appended claims. y

We claim: l

1. In a fluid operable pump having a valve outlet in said valve member, the improvement comprising forming said inlet so that communication is had between said inlet and said pumping means until the latter has attained its maximum capacity and has commenced discharging.

2. In a fluid operable pump having a valve member with `an inlet and an outlet and pumping means adapted to vary in volume between predetermined limits in order to transfer uid from said inlet to said outlet, the improvement comprising forming said inlet port so that the pumping means has attained its maximum volume a predetermined minimum time before the fluid communication between said pumping means and said inlet port is interrupted.

L3. In a fluid operable pump having an inlet port and an outlet port and piston-cylinder means for transferring fluid between said ports, the improvement comprising arranging said inlet port to communicate with said cylinder means until after said piston means has commenced its discharge stroke.

4. In a fluid pump, an inlet port and an outlet port, cylinder means adapted to communicate with said ports, piston means reciprocable in said cylinder means for drawing fluid therein from said inlet port and for discharging fluid therefrom into said outlet port, the said inlet port being adapted to communicate with said cylinder means at least until said piston means has commenced its discharging movement.

5. In a fluid pump, a valve member having a spaced inlet and outlet, cylinder means having i y l '2,437,089 f port means adapted to communicate with said inlet and said outlet, piston means movable in said cylinder means `for` drawing fluid therein from said inlet and for discharging fluid therefrom into said outlet, said inlet and said outlet being spaced apart a distance no greater than the diameter .of said port means and'said inlet being so located as to communicate with said port means until said piston has commenced its discharging movement. i

6. vIn a fluid pump, a plurality of substantially radially extending cylinders, a plurality of pistons reciprocable in said cylinders', a valve member centrally located relative to said cylinders and having an inlet and an outlet, port means in said cylinders adapted tov communicate successively with said inlet and said outlet, means adapted to be eccentrically positioned relative to said valve member and to engage said pistons for actuating the latter in response to rotation of said cylinders and pistons relative to said valve member, said inlet and said outlet being spaced on said valve member yby a distance not greater than the diameter of said port means, and said inlet being of substantially greater circumferential length than said outlet to maintain communication with said port means until said pistons commence their inward movement.

' 7. In a iluid pump, a rotor, a plurality of substantially radial cylinders in said rotor, a plurality of pistons reciprocable in said cylinders, a central bore in said rotor connected with said cylv inders, a valve member extending into said bore,

a piston actuating member in engagement with the outer ends of said pistons and adapted to be eccentrically located relative to said valve member so that rotation of said rotor is effective to cause said member first to move said piston outvalve member comprising an inlet port having arcuate ends adapted to communicate with saidv `wardly and then inwardly in said cylinders, said 6 said inlet port by a distance substantially equal to the diameter of the openings in said cylinders.

for actuating said rotor so as to cause said pistonsy to be reciprocated by said' member, said valve member comprising an inlet and an outlet each arranged in the plane of said -cylinders and symmetrlcally about the vertical center line or said valve member, said inlet-port` being adapted to communicate with said port means from prior to the beginning of the outward -movement of said piston means until after the beginning of the inward movementthereof, and said outlet having the ends thereof spaced from the ends of said inlet a distance substantially equal to or slightly less than the diameter of said port means.

GEORGE M. GEIGER. WALTER. ERNST.

REFERENCES 4GITED The following references are of record in the ille of this patent:

v UNITED STATES PATENTS Number Name Date 2,000,271: Benedek ..1 May 7, 1935 2,101,729 Benedek Dec. 7,' 1937 2,130,298 Ernst Sept. 13, 1938 2,220,636 Bischof Nov. 5, 1940 2,292,181 Tucker Aug. 4, 1942v Ferris Aug. 20, 1946 

